AB0290 COMPARATIVE FEATURES AND LONGITUDINAL BEHAVIOUR OF RHEUMATOID ARTHRITIS-ASSOCIATED UIP VERSUS IDIOPATHIC PULMONARY FIBROSIS: A SINGLE CENTRE COHORT STUDY
Authors: C. Mazeda, J. Antao, M. Ferreira, R. Aguiar, A. Barcelos, P. G. Ferreira
Journal: Annals of the Rheumatic Diseases (2022)

Background Interstitial lung diseases (ILDs) are a group of heterogeneous lung disorders with variable prognosis. Idiopathic pulmonary fibrosis (IPF) is the main idiopathic interstitial pneumonia and rheumatoid arthritis (RA) is the commonest cause of connective tissue disease related-ILD. In fact, ILD is the most frequent form of respiratory involvement in RA, with 10% patients having clinically significant disease, frequently imposing significant morbi-mortality. RA-ILD can potentially comprise different disease patterns with distinct prognosis, with usual interstitial pneumonia (UIP) being the most frequent radio-histological pattern. Several studies have suggested that the RA-UIP disease course and survival may be clinically similar to IPF. Objectives This study aimed to investigate comparative clinical features, longitudinal behaviour and healthcare resource utilization between local cohorts of RA-UIP and IPF patients. Methods Retrospective and descriptive study including all IPF and RA-ILD cases diagnosed and followed in the ILD outpatient clinic of secondary hospital between 2015 and 2020. All patients with RA diagnosis met classification criteria of 2010 ACR/EULAR and IPF patients were diagnosed according to 2018 ATS/ERS/JRS/ALAT clinical guidelines. Socio-demographic, clinical data and longitudinal lung function (functional vital capacity (FVC) and lung diffusion capacity for carbon monoxide (DL CO )) were collected. A statistical analysis was performed; p-value &lt;0.05 was statistically significant. Results: Table 1. Baseline clinical characteristics of all patients are listed in table. IFPn=22 RA-UIPn=14 p Age, years (mean±SD) 74.5±1.8 75.5±9.4 0.75 Sex (M/F), n 17/5 4/10 0.006 Smoking Status 0.31 Smoker (%) 0 0 Ex-smoker (%) 64.6 42.9 Smoking load 53.1±7.9 35.8±22.2 0.48 Baseline dyspnea (mMRC) 0.07 0 (%) 0 7.1 1 (%) 13.6 28.6 2 (%) 54.5 50.0 3 (%) 18.2 14.3 4 (%) 13.6 0 Cough (%) 86.4 42.9 0.01 Time from respiratory symptoms until diagnosis (months) 20.5±3.4 11.6±9.7 0.09 Elevated titers of Rheumatoid Factor, n - 10 Elevated titers of anti-CCP, n - 11 Baseline lung function FVC, % predicted 73.0±14.9 91.3±19.8 0.007 DLCO, % predicted 42.1±18.6 60.3±21.2 0.04 6-minute walking distance at baseline (meters) 341.8±147,7 346.2±132.3 0.95 In RA-UIP group, 86% of patients reported preceding articular symptoms, with lung disease being diagnosed after a median of 11 years (IQ range 2-13). All patients had a UIP/probable UIP pattern in HRCT. Regarding baseline FVC and DLCO, the RA-UIP group revealed better lung function compared to the IPF group. All patients with RA-UIP received some form of immunomodulation treatment. Around 78.4% of patients were on low dose prednisolone. Additionally, 64.2% received treatment with mycophenolate mofetil, 21.4% with rituximab, 7.1% with azathioprine and 7.1% with hydroxychloroquine. Regarding IPF patients, about 86.4% were treated with antifibrotics (nintedanib or pirfenidone). From the global population study only 27.3% and 14.3% of IPF and RA-UIP patients, respectively, were referred for respiratory rehabilitation. There were significant differences regarding FVC (p=0.002) and DLCO (p=0.003) decline over time between groups. Comparing to RA-UIP, IPF patients experienced a greater number of acute exacerbations (4 vs 27;p=0.06) and had more respiratory-related emergency visits. IPF patients also had a higher rate of hospitalizations, most of them respiratory-related. There was a clear trend towards higher mortality during follow-up in the IPF group compared to the RA-UIP group (40% vs 21,4%;p=0.23), although not reaching statistical significance. Conclusion RA-UIP patients appear to be less symptomatic and have a shorter symptomatic period at diagnosis. IPF patients had worse lung function at diagnosis. IPF patients showed a higher tendency to acute exacerbations and had a greater unplanned health care resources utilization. There was also a non-significant trend towards higher mortality during follow-up in the IPF group. Disclosure of Interests Carolina Mazeda: None declared, Joana Antao: None declared, Margarida Ferreira: None declared, Renata Aguiar: None declared, Anabela Barcelos: None declared, Pedro G Ferreira Speakers bureau: Boehringer Ingelheim, Novartis, Roche, Glaxo